There is a lot of controversy and even myth surrounding the use and inclusion of carbohydrates in the diet for our feline and canine companions. Unlike felines who are defined as obligate carnivores (1) meaning they only eat meat; canines are preferential carnivores (2). They can consume plant material if there is no meat to be sourced in the wild. Many believe that canines and felines can eat carbohydrates, but this is a pretty simplified idea and is usually based off of the fact that if a human give almost any dogs or some cats, fruits, vegetables or grains, they will eat it.
Carbohydrates are considered one of three energy sources (3) available aside protein and fats. This type of energy is sourced from other materials outside of proteins, amino acids, fats or fatty acids. Instead carbohydrates are found in plant materials including fruit, vegetables as well as grains (4).
There is not a dietary requirement for carbohydrates in the canine and definitely not in the feline diet (5, 6). Some sources reference a general guideline that if included in a diet, it makes up around 25%. By recommendation of many veterinarians, certain circumstances may require an adjustment in this percentage as some illness such as diabetes or cancer require an increase or decrease to address the illness and the body’s needs. This percentage however is very much over rated as carnivores have no requirement for carbohydrates and may further hinder the health of the companion. Many companion owners are misled to think that meat cannot have a positive effect on their companion’s health, however this is very untrue.
Carbohydrates include fruits, vegetables and grains. In addition to not being a dietary requirement they are defined as not having a complete amino acid profile (7, 8). A complete amino acid profile refers to a source that provides all needed amino acids to function. Carbohydrates also do not contain some essential vitamins and minerals that carnivores like cats and dogs require. This includes taurine (9) Vitamin D (10) and Vitamin B12 (11, 12). Carbohydrates furthermore have been shown to deplete Vitamin B and Vitamin C (see anti-nutrients below requiring larger amounts if carbohydrates are included in the diet.
Carbohydrates can be evaluated to determine its quality and how it could positively or negatively contribute to a companion’s diet. Despite the fact that fruits, vegetables and grains may provide some vitamins, mineral and colonic benefits, there seems to be many more draw backs than benefits.
There are varying levels of quality. The first is low quality. These carbohydrates all around provide no nutritional value to the companion causing more harm than good. These include ingredients that cannot be digested, are often genetically modified and cause severe health issues in many cases. Ingredients such as corn, soy and wheat are included in this list and are no-no ingredients 100% percent of the time (15, 16 17, 18, 19, 20, 21, 22, 23, 24)..
The second level are those that include anti-nutrients. Anti-nutrients are those that can be harmful to a companion’s health despite providing some other small benefits. The categories of anti-nutrients include the following:
Gluten. Gluten is the storage protein (25) found in many plant materials such as barley, oats, wheat and rye (26). Not all grains however, contain gluten which many companion animals are intolerant to. In combination with lectins that attach to the lining of the intestines a syndrome known as Leaky Gut Syndrome (27, 28) can result. This syndrome creates permeability in the intestinal wall allowing unwanted food particles to go directly into the blood stream (29). Not only does this mean absorption is not occurring properly, but harmful consequences for health overall. Although gluten is high in protein and fiber, there is little value to this ingredient and causes more harm than good in most individuals.
Oxalate Acid. Oxalate acid is found in many dark leafy greens such as spinach, chard and kale as well as many berries such as blueberries (30). Oxalate acid can prevent absorption of important nutrients and further exacerbate stone and urolith formation especially in companions that already have a history (31, 32, 33) .
Phytic Acid. Phytic acid is the storage form of phosphorus (34). Like oxalate acid, it can affect the absorption of many vitamins and minerals like zinc, iron, calcium and magnesium. Common sources include whole grains such as rice, legumes, seeds wheat and oats (35). Typically, the only way to reduce phytic content is to cook the ingredient (36), but then that particular ingredient now suffers nutrient depletion.
Solanine. Solanine containing carbohydrates, those in the Nightshade family like white potatoes, peppers and eggplant (37), can exacerbate inflammation in the individuals including further causing problems with allergies as well as joint pain (38).
Goitrogens. Goitrogens are carbohydrates that can interfere with proper thyroid function (39). Gotirogens often are found in the Brassica Family which include cruciferous carbohydrates like broccoli, brussel sprouts and cauliflower (40). They can also be found in some fruits and grains such as soy and millet. Even though a fully healthy individual can consume goitrogen containing carbohydrates in large amounts with no effect on the thyroid, it is a good idea to avoid them as thyroid conditions seem to have become an epidemic among our companion animals (41).
Finally, high quality carbohydrates are those that provide important vitamins and minerals as well as other healthful benefits without side effects. They are also ingredients that are highly digestible and bioavailable. Unfortunately, carbohydrates only have a bioavailability of about 70% versus that of meat which is well around 90-95% (42). This is highly noticeable in stool samples comparing companions on high carbohydrate diets versus those on meat diets. We notice a high frequency of elimination, larger sized stool and a stench we can all identify (43).
Sadly, this isn’t the end of the list counting against the problem with carbohydrates. There are also many health concerns in addition to those caused by the anti-nutrient carbohydrates. For example, some carbohydrates are extremely high in sugar such as corn, wheat, peas and carrots (44). Just like their effects in humans this can cause hyperactivity (45), not the good kind of energy needed for the body to thrive. This also can exacerbate diabetic companions or spike the blood sugar levels (46) resulting in an unbalanced state which affects many systems in the body. Sugar also is the primary energy source for cancer (47) allowing them to grow and take over the body. Sugar also can feed into inflammation (48, 49) which effects not only joints (50) but also inflammation in the brain that can lead to seizures (51, 52) among other organs and system problems.
Lastly looking at our feline and canine companions themselves with simple evaluation it can anatomically, chemically and physiologically be determined they are not designed to consume, digest or absorb potential nutrients from carbohydrates. The teeth of a carnivore are sharp, pointy and jagged made for holding, tearing, shearing, and crushing. The jaw moves vertically while the mouth also opens wide to consume large pieces of meat. Animals meant to consume plant material like rabbits or horses have flat teeth with jaws that move side to side (53, 54).
Amylase, an enzyme required to breaking down carbohydrates (55) and cellulase produced to break down cellulose (56) in plant cell walls are not made by canines or felines (57). They do however make the enzyme, trypsin, which is made in the pancreas specifically for breaking down meats (58, 59). The pancreas does have the ability to make a small amount of amylase but large carbohydrate loads are very stressful on the pancreas (60, 61, 62, 63).
Felines and canines also have a very short digestive tract (64) so food must be readily absorbable to be useful. With such a short tract there is no time to breakdown complex material like carbohydrates. Fat and protein however are easily digested (65, 66, 67).
At the end of the day felines are obligate carnivores and canines who only eat carbohydrates in dire situations (68) are not designed or meant to consume carbohydrates. Although many believe that canines and felines can eat carbohydrates regardless of potential quality there are too many drawbacks to completely ignore. Although we humans thrive on fruits, vegetables and grains along with meat, our companions are just not mean to consume this food source effectively and thus it is not the best addition to a companion diet.
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